An inspection system for imaging a vehicle using an X-ray is used for vehicle inspection. Specifically, an X-ray is transmitted through a vehicle to be scanned, to form an X-ray image of the vehicle, and an inspector may inspect inner details of the vehicle through the X-ray image without contact with the vehicle and damage to the vehicle. That is, the inspector can view goods loaded in a container without opening the container. A system for inspecting radioactive material is used to inspect radioactive material hidden in the inspected vehicle by means of inactive detection. Specifically, when the vehicle passes through the inspection system, if there is radioactive material, the inspection system may raise an alarm, and provides an approximate position of the radioactive material in the vehicle.
In practical applications in the field, the vehicle firstly passes through the system for inspecting Radioactive Material (RM) for inspecting whether radioactive material exist, and then is scanned by using an X-ray. When the radioactive material is inspected, the detection of the radioactive material starts when the vehicle arrives at the X-ray scanning and imaging apparatus, and ends after the vehicle completely passes through the scanning and imaging apparatus. A movement speed of the vehicle is calculated according to a time during which a probe is shielded and a length of the vehicle, to finally deduce a specific position of the radioactive material in the vehicle. The procedure comprises a warning start process, a warning peak process, and a warning end process. The above information is passed to the X-ray inspection system via an interface. In the X-ray image inspection system, when a beam is emitted by an accelerator, a detector starts to collect data, and when the accelerator stops emitting the beam, the detector stops collection and stores a complete image. The X-ray image is related to a scanning start time and a scanning end time of the device, a beam emission frequency of the current scanning, and a movement speed of the scanning device. The X-ray inspection system maps the position of the radioactive material in an inspection result of the radioactive material to an X-ray image. When the image is inspected, the specific position of the radioactive material in the vehicle can be intuitionally viewed, so as to facilitate a person who unpacks the container to rapidly find the radioactive source.
In practical applications, when scanning is implemented by using an X-ray, it is generally the case that a beam is firstly emitted and a scanning device starts to be moved to scan the inspected vehicle only after a dosage of the accelerator is stable. Therefore, there are some values of the air in the front of the X-ray image, instead of scanning the vehicle at the beginning. In addition, due to the position where the scanned vehicle is parked, when scanning is implemented, there may be large white spaces before or after the vehicle is scanned, and thus, the leftmost portion or the rightmost portion of the X-ray scanned image do not belong to the scanned vehicle. The detection of the radioactive material starts from the head of the vehicle, to provide a specific position of the radioactive material in the vehicle. As the starting points of the two inspection processes are different, the accurate position of the scanned vehicle in the X-ray image cannot be determined by the X-ray inspection system, which can only use the starting position of the image as a position of the head of the vehicle. Therefore, when the RM inspection result is mapped to the X-ray image, as the starting points of the two inspection processes are different and compression ratios of the two inspection images are different, a large deviation may be generated. Further, when the vehicle passes through the system for inspecting radioactive material, if the vehicle does not move at a constant speed, the result of the speed of the vehicle which is calculated by the RM system will also be influenced, which in turns influences the inspection result.
Further, as the two systems operate independently, an error in one-to-one correspondence between the inspection results of the two systems may be generated. In practical applications, many trucks may pass through a RM inspection system in sequence, and some inspection results may generated. Then, when the trucks pass through the X-ray inspection system, an order of these trucks may be changed for inspection, or some vehicles may directly be driven away without X-ray inspection. In this case, there may be a problem that an error occurs in the correspondence between the X-ray inspection image and the RM result.